Numerous methods and apparatus exist for dislodging and removing particulate materials that involve the impingement of a positive pressure fluid stream onto the surface containing the material or surface defined by the particulate material. Such operations are generally performed under one or some combination of the following circumstances; (1) the fluid stream is not controlled after impingement, (2) the apparatus being used must match the surface containing the particulate material such that a total enclosure results to contain the material-bearing stream after impingement, and (3) a vacuum system is used in conjunction with the positive pressure stream such that at least as much or more fluid stream is vacuumed away from, as is supplied by the positive pressure stream.
More generally, three basic fluid methods are known for mobilizing and transporting particulate materials; (1) processes using only suction, (2) processes using only pressure, and (3) processes using both suction and pressure.
Generally, according to the processes using suction, the mobilizing of materials and subsequent injection of the material into the suction system fluid stream for transport to a remote location is accomplished by having a small opening at the system entrance such that fluid velocities are sufficient to entrain materials close to the opening and/or by some mechanical assist such as a rotating brush or beater, a screw conveyor, etc. or by gravity. Such systems are used in floor, street, and yard cleaners and bulk material conveyors. Such systems require that the material being transported either pass through the prime mover or be collected between the source and the prime mover. Passing particulate materials through the prime mover restricts application to uses where some damage to the material or to the prime mover is acceptable, or to uses where the material is not abrasive to the prime mover. Having a collector between the source and the prime mover requires a collector structually sufficient to withstand the negative pressure within.
According to the processes using positive pressure primary fluid only, mobilization of, and injection of the material into the system for transport is accomplished by entrained secondary fluid drag like in a venturi nozzle, or by gravity, or by some mechanical means of isolation and transport against the pressure differential such as air lock rotating vanes. Relying upon secondary entrained fluid to mobilize and inject material into the positive pressure system is inherently inefficient. Depending upon a mechanical means to accomplish the same restricts application and efficient utilization of the internal fluid energy.
According to the processes using primary fluid in both suction and positive pressure, initial mobilization and injection of the material into the system is normally accomplished in the same manner as is the aforementioned processes using only suction; the distinguishing point being that in the combination suction-positive pressure process, substantial material transport is accomplished using the positive pressure part of the system. Such processes require material passing directly through the prime mover from the suction intake to the positive pressure exit or to bypass the prime mover by being separated from the material bearing fluid at the suction side, normally by a cyclone type apparatus, and then being reinjected into the positive pressure side, normally by some mechanical means such as an air lock.
The following are typical patents describing methods of the type pointed out above: U.S. Pat. No. 2,723,498 to Hastrup and Pinkerton, dated Nov. 15, 1955; U.S. Pat. No. 2,932,845, to Rydberg, dated Apr. 19, 1960; U.S. Pat. No. 3,048,876 to Kemnitz, dated Aug. 14, 1962; U.S. Pat. No. 3,075,227, to Bowles dated Jan. 29, 1963; U.S. Pat. No. 3,078,496, to Doran et al., dated Feb. 26, 1963; U.S. Pat. No. 3,306,672, to Kleiner et al., dated Feb. 28, 1967; U.S. Pat. No. 3,381,869, to Smith, dated May 7, 1968; U.S. Pat. No. 3,512,206, to Young, dated May 19, 1970; and U.S. Pat. No. 751,786, to Elston, Jr., dated Feb. 9, 1904.
In addition to providing a process without the short-comings of the procedures discussed above, this invention provides a means whereby a positive pressure fluid jet can be directly applied to, and transport therefrom, materials, with those advantages over a vacuum jet that are inherent to a positive jet, such as wide ranges of fluid energy control and action-at-a-distance from the jet nozzle, but without the disadvantages of controlling and containing the subsequent material-bearing positive pressure fluid stream that exist in known procedures.
This invention also provides a process and apparatus using a positive pressure primary fluid jet for dislodging and transporting materials, that is not limited in efficiency by having to rely upon entrained secondary fluid to dislodge and input materials into the primary positive pressure fluid stream, or that must have some mechanical means of injecting the material into the primary stream.
This invention further provides means for improving the ability of the positive pressure fluid jet to dislodge and mobilize particulate materials by disturbing or perturbating the stream via mechanical means thereby causing high frequency agitation of the particulate materials. These and other apparatus and processes for obtaining these results and advantageous over existing methods are more fully described below.